U.S. patent application number 16/597007 was filed with the patent office on 2021-04-15 for motor vehicle hybrid powertrain.
This patent application is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The applicant listed for this patent is GM GLOBAL TECHNOLOGY OPERATIONS LLC. Invention is credited to Suresh Gopalakrishnan, Lei Hao, Derek F. Lahr, Madhusudan Raghavan, Neeraj S. Shidore.
Application Number | 20210107348 16/597007 |
Document ID | / |
Family ID | 1000004426971 |
Filed Date | 2021-04-15 |
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United States Patent
Application |
20210107348 |
Kind Code |
A1 |
Shidore; Neeraj S. ; et
al. |
April 15, 2021 |
MOTOR VEHICLE HYBRID POWERTRAIN
Abstract
A vehicle powertrain includes a first power-source configured to
generate a first power-source torque and a multiple speed-ratio
transmission configured to transmit the first power-source torque
to power the vehicle. The powertrain also includes a fluid coupling
having a fluid pump shaft operatively connected to the first
power-source and a turbine shaft operatively connected to the
multi-speed transmission. The fluid coupling is configured to
multiply the first power-source torque, and transfer the multiplied
first power-source torque to the multiple speed-ratio transmission.
The powertrain additionally includes a second power-source
configured to generate a second power-source torque and a first
torque transfer system configured to connect the second
power-source to the first power-source. The powertrain further
includes a second torque transfer system configured to connect the
second power-source to the multi-speed transmission. A motor
vehicle having such a powertrain is also envisioned.
Inventors: |
Shidore; Neeraj S.; (Novi,
MI) ; Lahr; Derek F.; (Howell, MI) ; Hao;
Lei; (Troy, MI) ; Raghavan; Madhusudan; (West
Bloomfield, MI) ; Gopalakrishnan; Suresh; (Troy,
MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GM GLOBAL TECHNOLOGY OPERATIONS LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC
Detroit
MI
|
Family ID: |
1000004426971 |
Appl. No.: |
16/597007 |
Filed: |
October 9, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H02K 11/048 20130101;
H02K 11/0094 20130101; H02K 7/116 20130101; F16H 2200/0021
20130101; B60K 6/26 20130101; B60K 6/383 20130101; H02K 7/108
20130101; B60Y 2400/70 20130101; B60K 6/54 20130101; H02K 13/003
20130101; B60Y 2200/92 20130101; F16H 1/28 20130101; H02K 7/006
20130101; F16H 9/02 20130101; B60K 6/387 20130101 |
International
Class: |
B60K 6/54 20060101
B60K006/54; B60K 6/26 20060101 B60K006/26; B60K 6/383 20060101
B60K006/383; B60K 6/387 20060101 B60K006/387; F16H 1/28 20060101
F16H001/28; F16H 9/02 20060101 F16H009/02; H02K 7/00 20060101
H02K007/00; H02K 7/108 20060101 H02K007/108; H02K 7/116 20060101
H02K007/116; H02K 11/00 20060101 H02K011/00; H02K 11/04 20060101
H02K011/04; H02K 13/00 20060101 H02K013/00 |
Claims
1. A powertrain for powering a vehicle, the powertrain comprising:
a first power-source configured to generate a first power-source
torque; a multiple speed-ratio transmission configured to transmit
the first power-source torque to power the vehicle; a fluid
coupling having a fluid pump shaft operatively connected to the
first power-source and a turbine shaft operatively connected to the
multiple speed-ratio transmission, multiply the first power-source
torque, and transfer the multiplied first power-source torque to
the multiple speed-ratio transmission; a second power-source
configured to generate a second power-source torque; a first torque
transfer system configured to connect the second power-source to
the first power-source; and a second torque transfer system
configured to connect the second power-source to the multiple
speed-ratio transmission.
2. The powertrain according to claim 1, wherein each of the first
torque transfer system and the second torque transfer system is a
gear-set or a chain mechanism.
3. The powertrain according to claim 1, wherein: the multiple
speed-ratio transmission includes an input shaft; each of the first
power-source, the fluid coupling, and the input shaft is arranged
on a first rotational axis; the second power-source is arranged on
a second rotational axis; and the second rotational axis is
arranged parallel to first rotational axis.
4. The powertrain according to claim 3, wherein the first
power-source is an internal combustion engine, and wherein the
second power-source is an electric motor housed inside a motor
housing, the electric motor including: a rotor free to rotate
relative to the motor housing and having a rotor shaft operatively
connected to the first torque transfer system; and a stator having
a stator shaft operatively connected to the second torque transfer
system.
5. The powertrain according to claim 4, wherein the multiple
speed-ratio transmission includes a transmission case configured to
mount the multiple speed-ratio transmission to the first
power-source, the powertrain further comprising a first
torque-transmitting device configured to selectively couple the
stator to the transmission case.
6. The powertrain according to claim 5, wherein the stator shaft
includes a disc element extending radially therefrom, and wherein
the first torque-transmitting device is configured to selectively
couple the disc element to the transmission case.
7. The powertrain according to claim 5, further comprising a second
torque-transmitting device configured to selectively connect the
stator shaft to the second torque transfer system.
8. The powertrain according to claim 7, wherein the second
torque-transmitting device is a multiple-plate friction clutch or a
one-way clutch.
9. The powertrain according to claim 7, wherein the vehicle
includes an energy storage device configured to generate and store
electrical power for the first and second power-sources, the
powertrain further comprising a rectifier configured to convert
alternating current (AC) to direct current (DC) and slip rings
configured transfer electrical current to and from the stator.
10. The powertrain according to claim 9, wherein: each of the
stator and the rectifier is housed inside the motor housing, and
the slip rings transfer the DC current to the energy storage
device; or the rectifier is arranged externally to the motor
housing, and the slip rings transfer the AC current to the
rectifier for charging the energy storage device.
11. A motor vehicle comprising: a vehicle powertrain including: a
first power-source configured to generate a first power-source
torque; a multiple speed-ratio transmission having an output member
and configured to transmit the first power-source torque to power
the motor vehicle; a fluid coupling having a fluid pump shaft
operatively connected to the first power-source and a turbine shaft
operatively connected to the multiple speed-ratio transmission,
multiply the first power-source torque, and transfer the multiplied
first power-source torque to the multiple speed-ratio transmission;
a second power-source configured to generate a second power-source
torque; an energy storage device configured to generate and store
electrical power for the first and second power-sources; a first
torque transfer system configured to connect the second
power-source to the first power-source; and a second torque
transfer system configured to connect the second power-source to
the multiple speed-ratio transmission; and a road wheel operatively
connected to the output member to receive the first power-source
torque and/or the second power-source torque transmitted by the
multiple speed-ratio transmission.
12. The motor vehicle according to claim 11, wherein each of the
first torque transfer system and the second torque transfer system
is a gear-set or a chain mechanism.
13. The motor vehicle according to claim 11, wherein: the multiple
speed-ratio transmission includes an input shaft; each of the first
power-source, the fluid coupling, and the multiple speed-ratio
transmission input shaft is arranged on a first rotational axis;
the second power-source is arranged on a second rotational axis;
and the second rotational axis is arranged parallel to first
rotational axis.
14. The motor vehicle according to claim 13, wherein the first
power-source is an internal combustion engine, and wherein the
second power-source is an electric motor housed inside a motor
housing, the electric motor including: a rotor free to rotate
relative to the motor housing and having a rotor shaft operatively
connected to the first torque transfer system; and a stator having
a stator shaft operatively connected to the second torque transfer
system.
15. The motor vehicle according to claim 14, wherein the multiple
speed-ratio transmission includes a transmission case configured to
mount the multiple speed-ratio transmission to the first
power-source, wherein the vehicle powertrain additionally includes
a first torque-transmitting device configured to selectively couple
the stator to the transmission case.
16. The motor vehicle according to claim 15, wherein the stator
shaft includes a disc element extending radially therefrom, and
wherein the first torque-transmitting device is configured to
selectively couple the disc element to the transmission case.
17. The motor vehicle according to claim 15, wherein the vehicle
powertrain additionally includes a second torque-transmitting
device configured to selectively connect the stator shaft to the
second torque transfer system.
18. The motor vehicle according to claim 17, wherein the second
torque-transmitting device is a multiple-plate friction clutch or a
one-way clutch.
19. The motor vehicle according to claim 17, further comprising a
rectifier configured to convert alternating current (AC) to direct
current (DC) and slip rings configured transfer electrical current
to and from the stator.
20. The motor vehicle according to claim 19, wherein: each of the
stator and the rectifier is housed inside the motor housing, and
wherein the slip rings transfer the DC current to the energy
storage device; or the rectifier is arranged externally to the
motor housing, and the slip rings transfer the AC current to the
rectifier for charging the energy storage device.
Description
INTRODUCTION
[0001] The present disclosure relates to a multiple power-source
hybrid powertrain for a motor vehicle.
[0002] Modern motor vehicles frequently employ a powertrain that
includes a power-source, such as an internal combustion engine, a
multiple speed-ratio transmission, and a differential or final
drive. Such a multiple speed-ratio transmission may provide
automatic selection of discrete speed ratios and employ either
planetary or parallel gearing, or be configured as a continuously
variable transmission (CVT).
[0003] To produce a more motor efficient vehicle, hybrid vehicle
powertrains combine an electric motor and an internal combustion
engine. Torque from the engine and the electric motor is typically
channeled to the vehicle's driven wheels via the multiple
speed-ratio transmission. Efficiency of a hybrid vehicle powertrain
is generally related to the percentage of time that the engine must
be run in addition to or in place of the electric motor for
powering the vehicle.
[0004] Some hybrid powertrains employ a single electric motor in
combination with the engine. In such powertrains, transmission
output, as well as vehicle speed, is directly related to the speeds
and torques of the engine and the electric motor. Other hybrid
powertrains employ multiple electric motors in combination with the
engine to power the vehicle. Such electric motor(s) may be mounted
inside the multiple speed-ratio transmission, or be arranged
external to the transmission to apply the respective motor torque
either upstream of the input or downstream of the output of the
transmission.
SUMMARY
[0005] A vehicle powertrain includes a first power-source
configured to generate a first power-source torque and a multiple
speed-ratio transmission configured to transmit the power-source
torque to power the vehicle. The powertrain also includes a fluid
coupling having a fluid pump shaft operatively connected to the
first power-source and a turbine shaft operatively connected to the
multiple speed-ratio transmission. The fluid coupling is configured
to multiply the first power-source torque, and transfer the
multiplied first power-source torque to the multiple speed-ratio
transmission. The powertrain additionally includes a second
power-source configured to generate a second power-source torque
and a first torque transfer system configured to connect the second
power-source to the first power-source. The powertrain further
includes a second torque transfer system configured to connect the
second power-source to the multiple speed-ratio transmission.
[0006] Each of the first torque transfer system and the second
torque transfer system may be a gear-set or a chain mechanism.
[0007] The multiple speed-ratio transmission may include an input
shaft. Each of the first power-source, the fluid coupling, and the
input shaft of the multiple speed-ratio transmission may be
arranged on a first rotational axis. The second power-source may be
arranged on a second rotational axis, and the second rotational
axis may be arranged parallel to first rotational axis.
[0008] The first power-source may be an internal combustion engine.
The second power-source may be an electric motor housed inside a
motor housing. The electric motor may include a rotor free to
rotate relative to the motor housing and including a rotor shaft
operatively connected to the first torque transfer system. The
electric motor may also include a stator having a stator shaft
operatively connected to the second torque transfer system.
[0009] The multiple speed-ratio transmission may include a
transmission case configured to mount the multiple speed-ratio
transmission to the first power-source. The vehicle powertrain may
also include a first torque-transmitting device configured to
selectively couple the stator to the transmission case.
[0010] The stator shaft may include a disc element extending
radially therefrom. The first torque-transmitting device may be
configured to selectively couple the disc element to the
transmission case.
[0011] The vehicle powertrain may additionally include a second
torque-transmitting device configured to selectively connect the
stator shaft to the second torque transfer system.
[0012] The second torque-transmitting device may be a
multiple-plate friction clutch or a one-way clutch.
[0013] The vehicle may include an energy storage device configured
to generate and store electrical power for the first and second
power-sources.
[0014] The vehicle powertrain may further include a rectifier
configured to convert alternating current (AC) to direct current
(DC) and slip rings configured transfer electrical current to and
from the stator. Each of the stator and the rectifier, rotating or
stationary, may be housed inside the motor housing, and the slip
rings may transfer the DC current to the energy storage device.
[0015] The rectifier may be arranged externally to the motor
housing, and the slip rings may transfer the AC current to the
rectifier for charging the energy storage device.
[0016] The slip rings may be arranged along the second rotational
axis, either between the disc element and the second
torque-transmitting device or between the disc element and the
stator.
[0017] A motor vehicle employing such a powertrain is also
disclosed.
[0018] The above features and advantages, and other features and
advantages of the present disclosure, will be readily apparent from
the following detailed description of the embodiment(s) and best
mode(s) for carrying out the described disclosure when taken in
connection with the accompanying drawings and appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic illustration of a motor vehicle
employing a longitudinal powertrain that includes an internal
combustion engine and an electric motor connected in parallel with
a fluid coupling to a multiple speed-ratio transmission, according
to the disclosure.
[0020] FIG. 2 is a schematic illustration of a motor vehicle
employing a transverse powertrain that includes an internal
combustion engine and an electric motor connected in parallel with
a fluid coupling to a multiple speed-ratio transmission, according
to the disclosure.
[0021] FIG. 3 is a schematic illustration of an embodiment of the
motor vehicle employing a transverse powertrain shown in FIG. 2,
wherein the multiple speed-ratio transmission is a continuously
variable transmission (CVT), according to the disclosure.
[0022] FIG. 4 is a schematic stick diagram of one embodiment of the
powertrain shown in FIGS. 1-3.
[0023] FIG. 5 is a schematic stick diagram of another embodiment of
the powertrain shown in FIGS. 1-3.
DETAILED DESCRIPTION
[0024] Referring to FIGS. 1-3, a motor vehicle 10 having a
powertrain 12 is depicted. The vehicle 10 may include, but not be
limited to, a commercial vehicle, industrial vehicle, passenger
vehicle, aircraft, watercraft, train or the like. It is also
contemplated that the vehicle 10 may be a mobile platform, such as
an airplane, all-terrain vehicle (ATV), boat, personal movement
apparatus, robot and the like to accomplish the purposes of this
disclosure.
[0025] The powertrain 12 includes a first power-source 14
configured to generate a first power-source torque T.sub.i (shown
in FIGS. 1-5) for propulsion of the vehicle 10 via driven wheels 16
relative to a road surface 18. The powertrain 12 also includes a
multiple speed-ratio transmission 20, which may be an
automatically-shiftable, a.k.a., automatic, transmission. The
powertrain 12 may be mounted transversely in the vehicle 10 along a
general axis X, i.e., at approximately 90 degrees relative to a
longitudinal axis Y of the vehicle, wherein the transmission 20 is
configured as a transaxle--a transmission combined with a
differential or final-drive assembly. Such a transverse mounting of
the powertrain 12 is frequently employed for packaging purposes in
front-wheel-drive (FWD) vehicles, where the driven road wheel(s) 16
are arranged proximate a front end 10-1 of the vehicle 10.
Alternatively, the powertrain 12 may be mounted longitudinally in
the vehicle 10, along the axis Y. Such a longitudinal mounting of
the powertrain 12 is frequently employed in rear-wheel-drive (RWD)
or four-wheel-drive (4WD) vehicles.
[0026] In some vehicle configurations, the powertrain 12 may be
mounted longitudinally in the vehicle 10, i.e., substantially
aligned with the longitudinal axis X of the vehicle. In other
vehicle configurations, the powertrain 12 may be mounted
transversely in the vehicle 10, i.e., at approximately 90 degrees
relative to the longitudinal axis X of the vehicle. Such a
transverse mounting of the powertrain 12 is frequently employed for
packaging purposes in front-wheel-drive (FWD) vehicles, where the
drive wheel(s) 16 are arranged proximate a front end of the vehicle
10. In such vehicle configurations, the transmission 20 may be
combined with a final drive assembly and is generally described as
a transaxle. Although the longitudinal transmission embodiment of
the transmission 20 is specifically referred to below, the
disclosure is also applicable to transaxle configurations of the
transmission 20.
[0027] The transmission 20 is operatively connected to the first
power-source 14, i.e., externally mounted to the first power-source
and configured to transfer the first power-source torque T.sub.i to
the driven wheels 16. The transmission 20 is further configured to
receive and then selectively multiply, reduce, or leave unmodified
the first power-source torque T.sub.i to achieve a resultant
transmission output torque T.sub.o (shown in FIGS. 1-5) for driving
the vehicle 10. As shown in FIGS. 1-3, the driven wheels 16 may be
operatively connected to the transmission 20, such as via drive- or
half-shaft(s) 22, and configured to receive the transmission output
torque T.sub.o. A vehicle accelerator 24, such as a pedal or a
lever, is provided for the vehicle operator to control the first
power-source torque T.sub.i for driving the vehicle 10.
[0028] The first power-source 14 may be an internal combustion
engine, a fuel-cell, and/or an electric motor (not shown) mounted
in the vehicle 10 and having the transmission 20 mounted externally
thereto. However, for conciseness and clarity, the present
disclosure will concentrate on the internal combustion engine
embodiment of the first power-source 14. Accordingly, although the
numeral 14 should be seen as generally attributable to such
embodiments of the envisioned powertrain, for the remainder of the
present disclosure, the numeral 14 will be used to denote the
specific embodiment of the powertrain having solely the internal
combustion engine. As such, the first power-source torque T.sub.i
will be hereinafter also referenced as engine 14 torque. As shown,
the particular engine 14 may include a crankshaft 14-1 arranged on
the first rotational axis A1 for converting reciprocal motion of
its pistons 14-2 into rotational motion and generating the engine
14 torque. The vehicle 10 also includes an energy storage device
26, such as one or more batteries, configured to supply electrical
power to the powertrain 12, and specifically the first power-source
14 and various electronically controlled components of the
transmission 20.
[0029] As shown in FIGS. 1-5, the transmission 20 includes a
transmission housing or case 30 for retaining components of the
transmission's torque path 32 and mounting the transmission to the
first power-source 14. The transmission's torque path 32 provides
torque transfer within the transmission to enable selection of the
previously noted multiple speed-ratios and for operatively
connecting the engine crankshaft 14-1 to the drive wheels 16. The
transmission's torque path 32 is configured to receive the first
power-source torque T.sub.i and select an input-to-output speed
ratio of the transmission 20. Accordingly, the transmission's
torque path 32 generally includes components configured to receive
and/or transmit the engine 14 torque within the transmission 20, as
well as operatively interconnected and arranged along a torque path
centerline or one of the axes thereof. As shown in FIG. 1, the
torque path 32 may include a gear-train 34A. The gear-train 34A
includes a number of gear elements, such as one or more planetary
or epicyclic gear-sets (shown in FIG. 1), configured to provide a
predetermined number of selectable speed ratios.
[0030] The transmission's torque path 32 may also include one or
more torque transmitting devices 34B, such as clutches and brakes,
retained by the transmission housing 30. The torque transmitting
devices 34B are generally cooperatively configured to select
transmission speed-ratios and facilitate generation of a
predetermined amount of transmission output torque T.sub.o. A
transmission speed-ratio is generally defined as the transmission
input speed divided by the transmission output speed. Shifting from
one speed-ratio to another is typically performed in response to a
position of the vehicle accelerator 24 and assessed vehicle road
speed. Shifting between speed-ratios generally involves releasing
one or more "off-going" torque transmitting devices 34B associated
with the current speed ratio, and applying one or more "on-coming"
torque transmitting devices 34B associated with the desired
speed-ratio.
[0031] Alternatively, the transmission 20 may be configured as a
continuously variable speed ratio transmission (CVT), wherein the
transmission's torque path 32 may include a variable diameter
pulley system 34C (shown in FIG. 3), configured to provide a
continuously variable speed ratio. In general, a continuously
variable transmission (CVT), such as the CVT embodiment of the
transmission 20, is configured to change through an infinite number
of effective gear ratios between a maximum speed ratio and a
minimum speed ratio. A typical CVT includes two adjustable pulleys,
each having two sheaves. A belt or another suitable endless
rotatable device, such as a continuous loop cable or chain,
typically runs between the two pulleys, with the two sheaves of
each of the pulleys sandwiching the belt therebetween. Frictional
engagement between the sheaves of each pulley and the belt couples
the belt to each of the pulleys to transfer a torque from one
pulley to the other. One of the pulleys may function as a drive
pulley so that the other pulley may be driven by the drive pulley
via the belt. The speed ratio of the CVT is the ratio of the torque
of the drive pulley to the torque of the driven pulley. The speed
ratio may be changed by moving the two sheaves of one of the
pulleys closer together and the two sheaves of the other pulley
farther apart, causing the belt to ride higher or lower on the
respective pulley.
[0032] In each of the embodiments shown in FIGS. 1-3, the
transmission 20 is configured to provide a predetermined number of
selectable speed ratios or a continuously variable speed ratio,
respectively, and for operatively connecting the first power-source
or engine 14 and to transmit the output torque T.sub.o to the drive
wheels 16. The transmission 20 also includes an input member 36,
such as an input shaft, configured to receive the engine 14 first
power-source torque T.sub.i and transfer the subject torque via the
transmission's torque path 32. As also shown in FIGS. 1-3, the
input member 36 is arranged on and configured to rotate about the
first axis A1. The transmission 20 also includes an output member
38, such as an output shaft. The output member 38 is operatively
connected to the transmission's torque path 32 and is configured to
rotate about the first axis A1 (shown in FIG. 1) or about a third
axis A3 that is arranged in parallel with the first axis A1 (shown
in FIGS. 2 and 3). During operation of the powertrain 12, the
output member 38 is configured to output and pass on the resultant
transmission output torque T.sub.o.
[0033] As shown in each of FIGS. 1-3, the transmission input member
36 is selectively connectable to the engine 14 through a fluid
coupling 40, such as a torque converter. Generally, a torque
converter uses a transmission fluid supplied by a fluid pump 41.
Such a torque converter typically includes an impeller, a turbine,
and a stator, with the impeller being interposed between the stator
and the turbine. The stator alters the drive's characteristics of
the torque converter during periods of high converter slippage,
producing an increased first power-source torque T.sub.i or a
multiplication in converter output torque. The fluid coupling 40
may be housed within the transmission case 30 and arranged on the
first rotational axis A1. The fluid coupling 40 has a pump shaft
40-1 connected to and configured to drive the impeller. The pump
shaft 40-1 is operatively connected to the first power-source 14
and configured to receive the first power-source torque T.sub.i.
therefrom. The fluid coupling 40 additionally includes a turbine
shaft 40-2 operatively connected to the transmission 20 at the
input member 36, i.e., the transmission input shaft and configured
to transfer the converter output torque to the transmission 20. The
fluid coupling 40 may also include a torque converter clutch 40-3.
Application of the torque converter clutch 40-3 is actuated via
pressurized fluid supplied by the pump 41 and configured to lock
the turbine to the impeller. Locking the turbine to the impeller
causes all torque transmitted through the torque converter 40 to be
mechanical, thus eliminating losses associated with fluid
drive.
[0034] As shown in FIGS. 1-3, the motor vehicle 10 also includes a
differential or final-drive assembly 42 configured to transmit the
transmission output torque T.sub.o for driving an external load,
such as the driven road wheels 16. With continued reference to
FIGS. 1-3, the transmission 20 additionally includes a second
power-source 44 arranged in parallel with the fluid coupling 40,
operatively connected to each of the first power-source 14 and the
transmission 20, and configured to generate a second power-source
torque. Specifically, as shown in FIGS. 4-5, the second
power-source 44 may be an electric motor configured to apply an
electric motor torque T.sub.e to the driven road wheels 16 via the
transmission 20. As shown, the electric motor 44 is configured to
apply the electric motor torque T.sub.e in parallel with the first
power-source torque T.sub.i flowing through the fluid coupling 38.
The energy storage device 26 may be additionally configured to
supply electrical power to the second power-source 44.
[0035] The engine 14 and the electric motor 44 may be operatively
connected to the transmission torque path 32 at the input member
36. Accordingly, the transmission 20 is configured to receive the
first power-source torque T.sub.i and the electric motor torque
T.sub.e and output a sum of the first power-source and the electric
motor torques to drive a load, e.g., the driven road wheels 16. As
shown, the electric motor 44 is arranged on and configured to
operate with respect to a second rotational axis A2 that is
parallel to the first axis A1. As shown in FIGS. 4-5, the electric
motor 44 includes a motor housing 46 and a stator 48, which is free
to rotate relative to the motor housing. As shown, the stator 48 is
fixed to a stator shaft 48-1. The motor housing 46 is rotationally
fixed relative to the transmission housing 30, and may also be
mounted directly thereto. The electric motor 44 also includes a
rotor 50 fixed to a rotor shaft 50-1 and configured to rotate about
the second axis A2.
[0036] The powertrain 12 also includes a first torque transfer
system 52 configured to connect the second power-source 44 to the
fluid coupling 40. The first torque transfer system 52 is
specifically configured to transfer the second power-source torque
T.sub.e from the rotor 50 to the fluid pump shaft 40-1, and thus
add the second power-source torque T.sub.e to the first
power-source torque T.sub.i. The first torque transfer system 52
and the second torque transfer system may be configured as a
gear-set (shown in FIG. 4) or a chain mechanism (shown in FIG. 5).
The powertrain 12 additionally includes a second torque transfer
system 54 configured to connect the second power-source 44 to the
turbine shaft 40-2. Similar to the first torque transfer system 52,
the second torque transfer system 54 may be configured as a
gear-set (shown in FIG. 4) or a chain mechanism (shown in FIG. 5).
The second torque transfer system 54 is configured to transfer the
second power-source torque T.sub.e, and/or the first power-source
torque T.sub.i via the stator 48 to the transmission 20, thereby
contributing to the torque of the fluid coupling 40 or in bypass
thereof. The rotor shaft 50-1 of the electric motor 44 may be
either operatively or directly connected to the first transfer
gear-set 52. The stator shaft 48-1 is operatively connected to the
second transfer gear-set 54.
[0037] The powertrain 12 may additionally include a first
torque-transmitting device 56. The first torque-transmitting device
56 may be configured as a friction brake to selectively couple the
stator 48, i.e., engage to or disengage from, the transmission case
30. The stator shaft 48-1 may include a disc element 58 extending
radially therefrom. The first torque-transmitting device 56 may
then be configured to selectively couple the disc element 58 to the
transmission case 30. The powertrain 12 may further include a
second torque-transmitting device 60. The second
torque-transmitting device 60 may be configured to selectively
connect the stator shaft 48-1 to the second gear-set 54. The second
torque-transmitting device 60 may be configured as a multiple-plate
friction clutch (shown in FIG. 4) or a mechanical one-way clutch
(shown in FIG. 5). The stator 48 may be operatively connected to a
rectifier 62 configured to convert alternating current (AC), which
periodically reverses direction, to direct current (DC), which
flows in only one direction. The rectifier 62 may be configured to
rotate relative to the motor housing 46 and be housed together with
the stator 48 inside the motor housing, as shown in FIG. 4, or be
stationary relative to the motor housing, as shown in FIG. 5.
[0038] The powertrain 12 may also include slip rings 64 configured
to transfer electrical power to and from the stator 48. In other
words, the slip rings 64 may exchange power between the rectifier
62 and the energy storage device 26, or between the stator 26 and
the rectifier. In an embodiment where the rectifier 62 is arranged
inside the motor housing 46, such as on the stator shaft 48-1, the
slip rings 64 may extract DC current from the stator 48 to the
energy storage device 26. Alternatively, in an embodiment where the
rectifier 62 is grounded to or arranged external to the
transmission housing 30, the stator 48, the slip rings 64 may
transfer AC current to such an external rectifier, which may in
turn convert the AC current to DC current and then charge the
energy storage device 26. Alternatively, such a uni-directional
rectifier 62, which converts AC current to DC current, may be
replaced by a bi-directional device, e.g., an inverter (not shown)
which may transfer electrical energy from the energy storage device
26 to the second power-source 44, for motoring action. As shown in
FIG. 4, the slip rings 62 may be arranged along the second
rotational axis A2 between the disc element 58 and the second
torque-transmitting device 60. Alternatively, as shown in FIG. 5,
the slip rings 62 may be arranged along the second rotational axis
A2 between the disc element 58 and the stator 48.
[0039] Overall, the powertrain 12 is configured to generate
electrical energy, i.e., the second power-source torque T.sub.e,
across the fluid coupling 40, while reducing losses through the
fluid coupling. The powertrain 12 may employ an engine 14 with
cylinder deactivation or similar technology, where in a certain
fraction of engine's cylinders is deactivated based on engine load.
In such a powertrain 12, the slip of the torque converter 40 is
normally configured to account for the change in engine torsional
vibrations due to a varied number of firing cylinders. Because the
second power-source 44 provides a bypass for the torque through
torque converter 40, the robustness of slip control in the torque
converter 40 may be enhanced by assistance from the second power
source 44. For example, the amount of torque transferred through
torque converter 40 may be reduced, as compared to a powertrain
architecture without the second power source 44. As a result, the
force required to provide specific engagement of the torque
converter clutch 40-3 sufficient to maintain a certain amount of
slip inside the torque converter 40, may also be reduced. The
second power-source 44 may also be employed to provide the vehicle
10 with hybrid propulsion. The second power-source 44 may be
additionally employed to facilitate control of the slip in the
torque converter 40 during cylinder deactivation modes of the
subject engine 14 during speed-ratio shifts in the transmission 20
via the gear-train 34A and the torque transmitting devices 34B.
[0040] The powertrain 12 may operate in stop-start mode when either
the first torque-transmitting device 56 or the second
torque-transmitting device 60 is engaged. Specifically, in such a
stop-start mode, the electric motor 44 may be employed as an
alternator-starter for the engine 14. When the torque converter
clutch 40-3 is open or slipping at low differential speed and the
second torque-transmitting device 60 is engaged, the electric motor
44 may be employed as a generator across the fluid coupling 40,
reduce losses across the fluid coupling, and provide a bypass for
the second power-source torque T.sub.e to the transmission's torque
path 32, i.e., effectively circumventing the fluid coupling.
[0041] When the torque converter clutch 40-3 is open, slipping at
low differential speed, or locked, and the first
torque-transmitting device 56 is engaged, the powertrain 12 may
operate in generator mode, wherein at least some of the first
power-source torque T.sub.i is used to drive the electric motor 44.
Additionally, when the torque converter clutch 40-3 is open and the
first torque-transmitting device 56 is engaged, the second
power-source torque T.sub.e may be used to crank the engine 14 in
the stop-start mode. Furthermore, when the torque converter clutch
40-3 is open, the powertrain 12 may operate in one of two motoring
modes. For example, when the first torque-transmitting device 56 is
engaged and the second torque-transmitting device 60 is disengaged,
the electric motor 44 may be used to assist the engine 14 in
powering the vehicle 10.
[0042] The powertrain 12 may be controlled by a programmable
electronic controller 66 configured to achieve desired propulsion
of the vehicle 10 in response to command(s) from an operator of the
subject vehicle. Specifically, the controller 66 may be programmed
to control the first power-source 14, select transmission 20 speed
ratios, regulate operation of the first and second
torque-transmitting devices 56, 60, and activate the second
power-source 44 to generate a predetermined amount of transmission
output torque T.sub.o. The controller 66 may include a central
processing unit (CPU) that regulates various functions on the
vehicle 10, or be configured as a powertrain control module (PCM)
configured to control the entire powertrain 12, or a dedicated
transmission control unit (TCU) for controlling solely the
transmission 20. Configured as either a CPU or a PCM for the
powertrain 12, the controller 66 may be employed to control and
coordinate operation of the first power-source 14, the second first
power-source 44, and the transmission 20. In either of the above
configurations, the controller 66 includes a processor and
tangible, non-transitory memory, which includes instructions for
operation of the powertrain 12 programmed therein. The memory may
be an appropriate recordable medium that participates in providing
computer-readable data or process instructions. Such a recordable
medium may take many forms, including but not limited to
non-volatile media and volatile media.
[0043] Non-volatile media for the controller 66 may include, for
example, optical or magnetic disks and other persistent memory.
Volatile media may include, for example, dynamic random access
memory (DRAM), which may constitute a main memory. Such
instructions may be transmitted by one or more transmission medium,
including coaxial cables, copper wire and fiber optics, including
the wires that comprise a system bus coupled to a processor of a
computer. Memory of the controller 66 may also include a flexible
disk, hard disk, magnetic tape, another magnetic medium, a CD-ROM,
DVD, another optical medium, etc. The controller 66 may be
configured or equipped with other required computer hardware, such
as a high-speed clock, requisite Analog-to-Digital (A/D) and/or
Digital-to-Analog (D/A) circuitry, input/output circuitry and
devices (I/O), as well as appropriate signal conditioning and/or
buffer circuitry. Algorithms required by the controller 66 or
accessible thereby may be stored in the memory and automatically
executed to provide the required functionality of the powertrain
12.
[0044] The detailed description and the drawings or figures are
supportive and descriptive of the disclosure, but the scope of the
disclosure is defined solely by the claims. While some of the best
modes and other embodiments for carrying out the claimed disclosure
have been described in detail, various alternative designs and
embodiments exist for practicing the disclosure defined in the
appended claims. Furthermore, the embodiments shown in the drawings
or the characteristics of various embodiments mentioned in the
present description are not necessarily to be understood as
embodiments independent of each other. Rather, it is possible that
each of the characteristics described in one of the examples of an
embodiment may be combined with one or a plurality of other desired
characteristics from other embodiments, resulting in other
embodiments not described in words or by reference to the drawings.
Accordingly, such other embodiments fall within the framework of
the scope of the appended claims.
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